I have been taking Doxycycline Hyclate 100 mg for about a year. ...

I have been taking Doxycycline Hyclate 100 mg for about a year. Two pr day. I have had on occasions pain that is similar to heart pain. I now know that it is NOT heart. My Question: Do any of you take this tablet with food? With milk? On a Full stomach? On an empty stomach? The manufacturer gives NO directions on these questions! How do Pharmacists and Doctors arrive at their directions?? I take WITH food at breakfast and dinner. I stay away from dairy, calcium, iron etc for two hours before and after taking the Doxycycline Hyclate. The medicine is accomplishing what it is intended to do.